The present invention relates to a search system and special reproduction mode system for an information reproduction device, and particularly to a search system, a stroboscopic motion reproduction system, a still picture reproduction system and a still picture and sound reproduction system for an information reproduction device having a video memory.
There are known in the art two types of video disks, e.g., the constant-angular-velocity (hereinafter abbreviated as CAV) recording disk and the constant-line-velocity (hereinafter abbreviated as CLV) recording disk.
With the CAV disk, a fixed amount of information such as the quantity of video information for a frame is recorded on a track in each radial position of the disk. Disk portions, on each of which information corresponding to a vertical synchronizing signal located on the boundary between frames is recorded, are located in a straight line extending in the radial direction of the disk. As a result, the period of the synchronizing signal of a reproduced video signal is not disturbed immediately after a jump over the CAV disk, so that a reproduction mode such as the reproduction of a still picture may be properly performed.
With the CLV disk, however, the quantity of information recorded in the arcuate track at one radial position on the disk differs from that of the information recorded on the track at another radial position thereon. For example, the video information for one frame is recorded in the innermost circular track, while video information for three frames is recorded in the outermost track. As a result, the period of the synchronizing signal of a video signal obtained immediately after a jump over the disk is disturbed. For this reason, an information reproduction device including a video memory capable of storing the video signals for a frame or field is herein proposed. In this system, a reproduced video signal is converted into a digital signal through the use of a clock signal synchronized with the reproduced video signal, the digital signal is written into a prescribed position in the video memory, and the written digital signal is read therefrom through the use of an external stable clock signal. In this information reproduction device, portions, each of which corresponds to a frame or a field, can be extracted, at a desired period, from video information obtained from a recording disk and are then sequentially written into the video memory so that stroboscopic motion reproduction (scene extraction reproduction) can be performed. The interval of scene extraction for stroboscopic motion reproduction is not necessarily so definite that the interval can be easily determined by sight, and thus an indicator is provided therefor.